Process of evaporating liquids.



P. K'EST'NER. PROCESS GP EVAPOHATING LIQUIDS. APPLIGATIOH FILED 311111320, 1910 Patented July 11,1911.

"Gi ru t I To all whom it may concern:

PAUL K ESTNEB, OF L ILLE, FRANCE.

PROCESS OF EVAPOBATING LIQUIDS.

' Specification 0! Letter: Patent.

Patented July 11, 1911.

Application filed June 20, 1910. Serial No. 567,956.

Be it known that I, PAUL KESTNEIt,-fl citizen of the Republic of France, and a resitlcnt of Lille, Department. h'ord, ljrance, have invented an Im roved Process of ]Jvaporating Liquids, 0 which the following is a specification.

My invention relates to high densityconcentration and substantial desiccation of extracts such as extracts of wood, logwood, qucbracho, chestnut and many other vegetable and organic matters, and it comprises a method of evaporating viscous liquids contuinin; sensiti ve colloid matters wherein uch liquids are formed into a positively propelled lilm carried forward under the influence of an onrushing vapor current of relatively high speed; said film being heated for a very short period of time to atemperature above the normal boilimg point of water, and the heating being, continued until the material under treatment has lost suflieient water by evaporation to become solid on exposure to atmospheric temperature and ressure; the final stages of the travel of sai film being in a substantially vertical downward direction; all as more fully hereinafter set forth and as claimed.

To attain economy in the expense of carrihgo and iackin" of extracts and many iscous liquids, it has long been endeavored to carry concentration of the, same to dr ncss or substantially complete desiccation, or at least to a pasty or solid state approaclr illg dryness. More or less success has been achieved with some of these extracts by making the concentration under a reduced vacuum or under atmos )beric pressure with steam coils or steam he is. This operation, however, very long and diflit-ult; it is necessary to use steam at high pressure in the coil or steam belt, and the quality of the extract is often injured duringthe period of evaporation. Up to the present time, it has generally been understood that extracts are altered at high temperatures. While I have found this to begener ally truein up paratus used up to the present time, the liaility to change is due rather to the length of time of evaporation affdtl'te manner in which evaporation is"conducted,. rather than to the high temperature involved. .In a

way it may be said that in completing the.

evaporation or desiccation" of hose materials, time and temperature are reciprocalfactorss along exposure at a low temperature. may be, and frequently is, as injurious as a shorter exposure to a high tem erature. And, within due limits, the sheer egree of temperature used is not as important as the time of exposure thereto. If the time of ex; posure thereto be sufliciently brief relatively very high temperatures may be safely used and with advantage. By a suitable correlation of time and temperature, the temperature may be raised to a point where-all, or substantially all the moisture is removed before the material has time to suffer any damage. By using the process which I have developed, evaporation to dryness may be obtained without any alteration; notwithstanding the fact that during the process of concentrationthe material under treatment has been temporarily subjected to temperalures above 100 C.

To put in n'actice my improved process in the embodiment of the present case, I preferably commence with the liquid extract already concentrated to a relatively high density in any ordinary up mratus. This material is fed to elongatec evaporating tubes disposed vertically, and such apparatus should consist. of at least two tubes having their upper ends connected so as to se' cure a complete and rapid circulation of the .mat'rial fed to the lower end of one of said which the described process may be carried out; a plurality of casings each with a pair of circulatin tubes being employed; Fig. 3,

is a view il ustrating another form of apparatus capable of carrying out my improved process having a plurality of circuating tubes within a single casin", with a desiccating chamber connect the discharging tube; Fig. A, is a view illustrating still another form of apparatus pvhich may be employed, comprising a lurahty of casings, one curryin an ascenmg tube, and theother a deseen mg tube; Fi 5, 1s a modified form of apparatus availab e for use m carrying out in improved process, ii1 which the material is fed at the (1 to the end of r upper portion of the structure, such apparatus being. also provided with a desiccating chamber, and Fig. 6, is another -modified form of structure, alsoarailable for the process, having a separating chamber at the use communicating with the downwardly discharging tubes. i

In the drawings herewith, .l' represents a reservoir containing material to-b'e concern" trated; 2 a pump for delivering theimaterial to the a paratus in a continuous manner against t c pressure t lierein; f3 a substan'-. tially vertical tube or tubes-in which. the material ascends; 4 a substantially vertical tube or tubes in which it descends;5 a-shell inclosin the tubes and receivin the, heating met rum which may enter at't he poin't 6, and 7 is a reservoir into which the concentrated material may be discharged.

As here shown, 7. indicates a simple open tank.. As the finished material leaves the descending tube or tubes, the accompanyingwater. vapor goes oil into the air while the "desiccated but hot and still-fluid mix-- terial fallsinto the tank where it soon becomes solid on cooling. It still carries some moisture, andmust have atthe point of discharge sufi'icient to enable it to be fluid at such oint' but this amount isnot, in the preferre form'of.this invention, suflicient to enable it to remain fluid --at ordinary temperaturw so that uponcoolingitsets and solidifies. In anothert'modification' of this invention, in lieu of discharging the material at atmospheric pressure, I may discharge-itinto a vacuumtank where the re maining moisture will alsoflaslrinto vapor. vcsiculating the mass and rendering it light and fluffy, but, this J] do not specifically' claim herein, it forming. thespecifie subject matter of my mpen'ding up hcation, Serial No. 490,804. Inste d of iscliarginglthc concentrated,material into said openjreser voir, however, I may discharge it into n separating chamber 8,- as illustrated in Fig. 2, from which the concentrated liquid may ;escape by a pipe" to asintabic re eptacle; which may be the open tank 7.; 'lhcvapor may :pass oil at 10, preferably through a baclcprcssum valve,- indicated at ll. in order to produce a suitable. back pressure-to permit an elevation of temporal are desirable for i-crtain extracts very dillirfultt'o dehydrate and .which have a' high boilingpoi lit. "lhe separated vapor may be lcdto'any' desired p'oint ofuse.

it will be understoodthatfif 'lio'uid previously heated be delivered rr'urulurlyand continuously to the lower end of an asciil'ul- ?ing tube or tubes 3; a heating! medium bring simultaneously admitted, preferablywade:- pressure. to lbo shellQvupor will be produced in such liquid as soon as it nan-hes the portion'of the tularwilhin the shell. and with this vaporwill drive forward the -tain velocity of theva accompanying liquid in 'the manner of the climbing film type of evaporators; that is to say, that in proportion as the liquid adand consequently its velocity. When a ceror current is reached. the li aid 13 entraine and carried forwar as a tiin film on the inner surface of the the vapor and'the liquor entrained b the vapor,- pass into the second tube; the ,iquid in a thin travelin film passing over the length of the sur'ace, and the current of vapor occupying the central space. It will be readily understood, therefore, that the slower the material is fed into the apparatus. the thinner will be the traveling film and the greater will be the extraction of the watery content and the greater will be the concentration of the material discharged. By giving the tubes the proper correlation of length and diameter, it is easy and possible to dry most extracts to such an extent that on cooling they will become absolutely solid and brittle without the' necessity of subjectingjhem to -further desiccation byfthe action of a drier.

Extracts flow with eatdifliculty at the consistency at which t ey leave the ordinary forms of concentrating apparatus, and it is for this reaso that their further concentration in such ordinary apparatus is substantially impossible.

.vances in a tube, the flow of vapor increases,

tube. Arriving at the top of the apparatus, 4

In the apparatus which I have shownand described it will be seen that it is in the descending tube that final concentration is effected, it being easier to make stiti liquids flow downward. The extract bcin carried downward by the vapor whic passes through the tube with great velocity, the material is forced to descend even if very viscous.

It is important in operatin the process that the tubes be in a vcrtiea or approximately vertical position. since a non-vertical position leads to irregularities in the. distri- --bution of the filmiform liquid in the. as-

cending tubes, and of the. thin falling film in the descending tubes. It is also im ortant that the. length of the tube be ('Oflfiit arable, or, rather, that the ratio between the length of the tubes and their diameter be such as to insure the desired velocity in the travel of the vapor and li uid under treatment. it is by correlating t lNSG conditions that T am able to obtain the velocity of vapor nw'vss'ury to distribute. the extract iua thin film on the inner surface. of the tubes, and to I causo the duration of the passage through us to be so brief that I am able to avoid any substantial alteration in the product.

'l igz. 2 represents another variation and shows an apparatus carin 'ingr l'our tubes in which the first pair of lobes arc in a diil'u-rarrangement is recoxmnnded for particu- Parly diflicult concentrations and where eeonom in height is desirable,since the four tubest n'ee meters in len 'th will serve the same pur length. n the same way, it is possible to have a greater number of communicating tubes, six for example. In this formpf the apparatus the liquid passes to a special se arating chamber instead of being directly dischar ed into a receptacle open to the atmos iere.

In ig. 4, a variation is represented in which each tube has its separate heating shell permitting independent heating.

Fig. 5 represents an apparatus containing three tubes in which the point of feed of material to be treated is at the upper end of one of said tubes.

In Fig. 6, another form of apparatus having three tubes is shown; the material to be treated being fed to the lower end of an as pending tube. and descending in a plurality of tubes.

It will be understood that any degree of pressure above or below atmos )heric may be maintained in the receptacles, ut if there is any degree of vacuum therein and the material is so passed through the. apparatps as to finish with moisture capable of self-evaporation at the finishing temperature, the result. will be a vesiculation, or flailing of the material in such receptacle, as more specifically described and claimed in the acknowledged a :plication.

It will be understood that an indefinite number of.groups of the tubes can be provided, but the last passage ofthe liquid under treatment should be made in a descending tube. The apfmratusin. question may consist of a :mgle serpentine tube in lieu of'tnbcs connected to chambers. ]l v serpentine is meant an assembly of several tubcs so'connected that a continuous passage of liquid through the same may be offectcd, and it is evident in practice that it. will be possible to employ as many. serpenti'ncs in the shell as the power of evaporation I'Ut uired by the apparatus demands.

ihrdina'rily, the apparatus should not work under vacuum, since this prevents the attainment. of the temperature desired and the pressure should be at least suflicicnt to allow the vapor to escape tothe atmosphere. Qtherwise the temperature would be too low and the extract could not cool; In many cases it may be desirable to give a bar pressure to the exhaust to raise the pressure so as two to es six meters in and therebythe temperature in the apparatus. However, when I wish to utilize exhaust steam in making the concentration, it may become necessary to work the apparatus under a slight vacuum to make the concentration at a temperature slightly below 100 C. When working under )IBSSUIB it is necessary to use a pump to orce the material to be treated into the a )paratus; under other conditions, however, tlus pump may be replaced by any appropriate apiaratus for feeding the liquid into the tu es, and in some instances a gravity feed may be employed.

By the use of this process I have succeeded in concentratiug'wiml washings and wood pulllp washings so as to obtain hard extracts, an I have also concentratedmolasses and sugar juices obtainedfrom different sources and secured solid products on cooling.

I claim:

1; The )rocess of concentrating viscous liquids, wiich comprises evaporating at a re atively low tempefltture until such liquids assume a thick and concentrated consist-.

' ency, and then rapidly passing such concentrated liquid through a zone of materially higher temperature and evaporating the same in transit.

2. The recess of concentrating viscous liquids, w i'ieh comprises evaporating at a re atively low tem rature until such liq-' aids assume a thic and concentrated consistency, then rapid] passing such concentrated liquid through a zone of materially higher temperature for evaporation in transit,.,and discharging said liquid'in adownward direction. 7

3.'.The process of desiccating thick liquids, which comprises rapidly passing a traveling film of such liquid through a zone of relatively high temperature, the temperature and the time of passage being so correlated that a sullicient amount of the moisture present is evaporated, Iprior to in-- jurious changes occurring, to al ow'the liquid to solidify upon cooling, and cooling the treated liquid to a solidified mass.

4. The process of desiccating thick liquids, which comprises rapidly passing a traveling film of such liquid through a zone of relatively high temperature and pressure, the temperature and t e time of passage be ing so correlated that a, sullicicnt amount of the moisture present is evaporated, 'riorto injurious changes occurring, to al ow the liquid to solidify upon cooling, and cooling the treated liquid to a solidified mass.

5. The process of desiccating thick liquids, which comprises rapidly passing a traveling film ofsuch liquid through a zone of relatively high tel'n eraturc and pressure; the temperature and t is time of passage being so correlated that a. suflicient amount of the moisture present isevaporated prior to s 7.- The process of desiccating thick liquids,

' relatively hi h temperature and the time of amount of the moisture occurring to allow the liqon cooling, and-releasing permitinjurious changes uid to solidify u the pressure un er circumstances ting the treated liquid to solidify. t

6.. The process of desiccati thick liqaids, which I comprises rapidly 'passin such liquid as a traveling film up avertica' steam-heated tube and then down through a similar tube, both passages being made at a relatively l i 'h temperature and the time of passage an the temperatures within the tubes being so correlated that a sufficient amount of themoisture present is evaporated, prior to injurious changes occurring to allow. the liquid to solidify u on cooling, dischar 'ng the liquid, and al owing such remove liquid to set to a solid mass;

which comprises rapidly passing such liquid asatraveling ii to up a vertical steamheated tube and then down through a similar' tube, both passages being made at a passage. an the temperatures within the tubesbeing so correlated that a snilicient resent is evaporated prior to injurious c ranges occurring toallow the liquid to solidify upon cooling, discontinuin the passage and removing the, treated lquidupon the removal of this amount .of moisture, and allowing such removed li aid to set to a solid mass.

8. In t n: concentration and desiccation of J liquids, the process which comprises conccntrating a ,liquid to a thick consistency. l transmitting the thickened liquid as a l rapidly traveling film through a zone of I rcntivclyhigh tcm x rature and pressure,

the tem raturc and time of passage lasing l so corrc ated that a suilicient amount of tho moisture still present is removed. prior to injurious. changes occurring, to allow tho treated liquid tos'ct upon cooling. and r ot,

no its sett ng.t0;a, soliditicd tnthjs i 9. 'ln theconcentration and dosh-ta transmitting the thickened liquid as a rapidly traveling film through a plurality of vertjc'ally arranged heated tubes, the passage through thc'lastof said tubes being in a downward direction and saidtubes being maintained .at relatively high temperatures, the tem )eratures and time of passage bein so come ated that a sufiicient amount of tie moisture still present is removed prior to injurious changes occurrin to allow the treated liquid to set upon coo ing, and cooling the liquid under circumstances permit-ting its settingto a solidified mass.

10. In the concentration and desiccation of liquids, the process which comprises concentrating a liquid to a thick consistency,

transmitting the thickened liquid as a.

rapidly traveling film through a zone of relatively high temperature and pressure, the tenqicrature and time of passage being so corrc ated that a sullicicnt amount of the moisture still present 18 removed prior to injurious changes occurring to ul ow the treated liquid to set upon cooling, and discharging the treated liquid at atmospheric pressure.

ll. In the concentration unddcsircation of liquids. tho proccss whirh con'qu'isesconcontrating a liquid to a thick consistency, transmitting the thi kened liquid as a rapidly travolpig tihn through a' zone'of ;rcluti\'oly high tt-nqa-raturtand pressure,

the tcnqmratnrc and-limo of' passage being so correlated that a sullit icnt amount of the moisture still present is removed prior to injurious changes occurring to al ow. the ll'lillttl liquid to set upon cooling. and discharging the treated liquid at atmospheric press-urtlln'ough a chamber maintained at an lllltl'lllt'tllilll' prwsuro.

In testimony Win-rout. l have signed my nannto lliis'spm-llitztllull, in the presence of two subscribing witnesses. s

lAl li KFSTNER.

W it'nossos s l lltlNltl tmnancn, 

